1. Field of the Invention
This application relates to a sheet conveying device that feeds a sheet, e.g., a recording sheet or a document, multiple times through the sheet conveying device, and to a duplex recording device including the sheet conveying device.
2. Description of Related Art
Known duplex recording devices, such as those described in Japanese Unexamined Patent Application Publication No. H11-209008 A may record on both sides of a recording sheet by feeding a recording sheet using a feed roller to a conveying path and by again feeding the recording sheet using the same feed roller to the conveying path. Known printing devices may have a feed roller disposed above a feed tray. In the feed tray, a sheet holder for holding recording sheets is biased upwards by a spring. Therefore, the recording sheets held in the feed tray are pushed against the feed roller. In this state, forward rotation of the feed roller causes the recording sheets to be fed from the feed tray to a conveying path. A recording unit records an image onto one side of the recording sheet as the recording sheet is conveyed along the conveying path.
This printing device also has a sheet feed guide along which the recording sheet having the image recorded on one side thereof is conveyed in the reverse direction. The sheet feed guide is inclined from a downstream side of the recording unit in the conveying path towards one end of the feed tray, which is adjacent to the feed roller. The recording sheet guided by the sheet feed guide is conveyed to a position between the feed roller and the recording sheets in the feed tray. Forward rotation of the feed roller causes the recording sheet guided by the sheet feed guide to be fed to the conveying path. The recording sheet is flipped over while being conveyed in the conveying path. Then, an image is recorded on the reverse side of the recording sheet by the recording unit, and the recording sheet is discharged.
Nevertheless, if a recording sheet conveyed in the reverse direction along the sheet feed guide is not properly guided to a position between the feed roller and the recording sheets in the feed tray, sheet jamming may occur.
In known printing devices, the topmost recording sheet placed in the feed tray is moved in a direction opposite to the conveying direction. This prevents the topmost recording sheet from being fed along with the recording sheet guided by the sheet feed guide. Nevertheless, because the recording sheet guided by the sheet feed guide and the recording sheet disposed directly below the topmost recording sheet contact each other, these recording sheets may be fed together to the conveying path. A sheet conveying device used as document conveying means in a scanner has a similar problem. In particular, a document conveyed in the reverse direction may become jammed, or a document placed in a feed tray or document tray may be fed along with the document conveyed in the reverse direction.